The invention relates generally to medical connectors of the type used in the handling and administration of parenteral fluids, and more particularly, to a needleless connector employing a valve mechanism that compensates for negative fluid displacement, i.e., drawing of fluid into the outlet end of a connector, during deactuation of the valve.
Within this specification the terms, xe2x80x9cnegative-bolus effect,xe2x80x9d xe2x80x9cpositive-bolus effect,xe2x80x9d and xe2x80x9cno-bolus effectxe2x80x9d are used to describe the operating characteristics of medical connectors during deactuation of the valve mechanisms contained within the connectors. Negative-bolus effect describes the condition during which fluid is drawn into the connector during deactuation. Positive-bolus effect describes the condition during which fluid is flushed out of the connector during deactuation. No-bolus effect describes the condition during which fluid displacement is neutralized and fluid is neither drawn into nor flushed out of the connector during deactuation.
Needleless medical connectors for injecting fluid into or removing fluid from an intravenous (IV) system are well known and widely used. Conventional needleless medical connectors generally include a housing having an inlet port and an outlet port. The inlet port is sized to receive a blunt male cannula, such as a male Luer taper. Disposed within the inlet port is a valve mechanism that provides access to a fluid path that communicates with the outlet port. In some connectors, the fluid path is defined by the internal boundaries of the connector housing, in other connectors it is defined by an internal cannula or hollow spike, still in others, the fluid path is defined by a compressible tubular body which carries the valve mechanism. The outlet port of the connector is typically connected to IV tubing which in turn is connected to an IV catheter that communicates with a patient""s venous system.
Many needleless medical connectors create fluid displacement during actuation and deactuation of the valve mechanism. During actuation, the blunt male cannula is inserted into the inlet. In some connectors, the cannula passes through the valve mechanism to establish fluid communication with the fluid path. In other connectors, the cannula merely displaces the valve mechanism, without penetrating it, in order to establish fluid communication with the fluid path. In either case, the volumetric capacity of the fluid path is often reduced by the insertion of the blunt cannula. Subsequently, when the blunt cannula is removed from the connector, the volumetric capacity of the fluid path increases. This increase in the volumetric capacity may create a partial vacuum in the fluid path that may draw fluid into the connector from the outlet end. As previously mentioned, the effect of drawing fluid into the connector in this manner is referred to as a xe2x80x9cnegative-bolusxe2x80x9d effect in that a quantity, or xe2x80x9cbolus,xe2x80x9d of fluid is drawn into the partial vacuum or negative pressure location; i.e., the connector.
A negative-bolus effect is undesirable in that the partial vacuum created within the connector may draw fluid from the IV tubing. The IV tubing in turn draws fluid from the IV catheter which in turn draws fluid, e.g., blood, from the patient""s venous system.
The negative-bolus effect may be reduced by undertaking operational safeguards. For instance, prior to the removal of the blunt cannula from the connector, the IV tubing may be clamped off between the connector output port and the IV catheter. This prevents the backup of blood through the IV catheter. If a syringe with a blunt cannula tip is used to inject fluid into the inlet port of the valve, the syringe may be continually depressed while the syringe is disengaged from the connector. The continued depression of the syringe injects fluid into the fluid path to fill the increasing volume thereby reducing the chance of a partial vacuum forming in the fluid path and a negative bolus. However, both of these approaches are undesirable in that the operator must remember to perform an additional step during removal of the syringe or other device from the connector rather than the steps being taken automatically by the connector.
The negative-bolus effect may also be reduced by the design of the medical connector. As previously mentioned, some medical connectors include an internal cannula or hollow spike housed inside the connector body. The internal cannula or spike is positioned to open a septum upon depression of the septum onto the internal cannula or spike by a blunt cannula. The internal cannula or spike has a small orifice at the top and upon depression of the septum is put in fluid communication with the blunt cannula. The internal cannula or spike provides a generally fixed-volume fluid-flow path through the connector. Thus, as the septum returns to its closed position the partial vacuum formed within the connector is not as strong as the vacuum formed in a connector having a more volumetrically dynamic fluid path. A disadvantage of typical connectors having an internal cannula or spike is a lower fluid-flow rate. This low flow rate is caused by the small orifice in the cannula or spike. Additionally, it has been noted that with the connector design having a fixedly-mounted internal spike and a movable septum that is pierced by that spike to permit fluid flow, such pierced septum may be damaged with multiple uses and a leaking connector may result.
Other connectors provide a valve mechanism that includes a flexible silicone body and a rigid spring leaf positioned about an internal cannula. Upon depression of the valve mechanism by a blunt cannula, the internal cannula forces the leaves of the spring leaf apart, the leaves in turn force the top of the body apart and open a slit contained therein. The opening of the slit establishes fluid communication between the blunt cannula and the internal cannula. The body includes a side reservoir that expands upon depression of the valve mechanism and receives fluid. Upon deactuation of the valve mechanism the reservoir collapses between the connector housing and the spring leaf and fluid is forced out of the reservoir into the internal cannula. This displacement of fluid may fill the partial vacuum being formed by the deactuation of the valve mechanism and thus reduce the possibility of fluid being drawn into the connector.
Although these connectors may reduce the negative-bolus effect, they have several disadvantages. First, during periods of nonuse, residual fluid left within the collapsed reservoir is likely to dry and adhere to the leaf spring. This may cause particulate to enter the fluid path during subsequent actuation or may even prevent the reservoir from expanding during subsequent actuation. Second, the connector employs a complex two-part valve mechanism that requires an internal cannula for actuation and deactuation. The complexity of this device lends itself to manufacturing difficulties and increased manufacturing costs. Third, during actuation of the valve mechanism, the leaves of the rigid spring leaf may cut through the body and cause a leak.
Hence, those concerned with the development of medical connectors have recognized the need for a medical connector having a valve mechanism that avoids the negative-bolus effect by producing either a positive-bolus effect or a no-bolus effect. The need for a medical connector that provides these effects without sacrificing fluid-flow rate or structural simplicity has also been recognized. The present invention fulfills such needs and others.
Briefly, and in general terms, the invention is directed to a medical connector having a valve mechanism that provides either a positive-bolus effect or a no-bolus effect, upon deactuation of the valve mechanism.
In a first aspect, the invention is directed to a needleless connector for medical use, adapted to facilitate the flow of fluid therethrough. The connector includes a housing having an inlet port and an outlet port. The connector also includes a flex-tube assembly defining a fluid path between the inlet port and the outlet port. The flex-tube assembly is movable between uncompressed and compressed states and has a first internal volume when in the uncompressed state and a second internal volume, at least as great as the first internal volume, when in the compressed state.
By providing a flex-tube assembly having an internal volume when compressed, e.g., activated by the insertion of a blunt cannula, that is at least as great as the internal volume when the flex-tube assembly is uncompressed, the possibility of a partial vacuum forming within the fluid path defined by the flex-tube assembly upon removal of the blunt cannula is essentially eliminated and instead, a positive-bolus effect or a no-bolus effect is provided. Thus, fluid is prevented from being drawn into the connector through the outlet port upon removal of the blunt cannula.
In more detailed aspects, the second internal volume is greater than the first internal volume. In another detailed facet, the second internal volume is substantially equal to the first internal volume. In yet another detailed aspect, the flex-tube assembly includes an inlet end that is positioned within the inlet port during the uncompressed state and outside the inlet port during the compressed state. The flex-tube assembly also includes a bore carried by the inlet end. The bore is closed when the inlet end is within the inlet port and opened when the inlet end is outside the inlet port. In a further more detailed aspect, the flex-tube assembly includes a flex-tube insert having at least one collapsible section movable between uncollapsed and collapsed states. The flex-tube assembly also includes a flex-tube piston that surrounds the flex-tube insert and defines the fluid path. The flex-tube piston includes a piston head that is positioned within the inlet port during the uncompressed state and outside the inlet port during the compressed state. The flex-tube piston also includes a bore that is carried by the piston head. The bore is closed when the piston head is within the inlet port and opened when the piston head is outside the inlet port. The flex-tube piston further includes a piston base that is proximal the outlet port and in communication therewith. The flex-tube piston is responsive to the movement of the flex-tube insert. In another aspect, the flex-tube insert includes one collapsible section and the first end is secured within the piston head and the second end is secured within the piston base.
In yet another aspect, the flex-tube insert includes two collapsible sections and a middle support for joining the two collapsible sections. For one collapsible section, the first end is secured within the piston head and the second end is pivotably attached to the middle support. For the other collapsible section, the first end is pivotably attached to the middle support and the second end is secured within the piston base. In another facet, the flex-tube assembly includes at least one collapsible section defining the fluid path, a piston head that is positioned within the inlet port during the uncompressed state and outside the inlet port during the compressed state, and a bore that is carried by the piston head. The bore is closed when the piston head is within the inlet port and opened when the piston head is outside the inlet port. The flex-tube assembly also includes a piston base proximal the outlet port and in communication therewith.
In yet another facet, the flex-tube assembly includes one collapsible section and the first end comprises the piston head and the second end comprises the piston base. In still another facet, the flex-tube assembly includes two collapsible sections and a middle support for joining the two collapsible sections. For one collapsible section, the first end includes the piston head and the second end is pivotably attached to the middle support. For the other collapsible section, the first end is pivotably attached to the middle support and the second end comprises the piston base.
In a second aspect, the invention is related to a valve for providing a fluid path between the inlet port and outlet port of a connector. The valve includes a flex-tube insert that is substantially axially aligned with the axis of the fluid path. The insert is movable between uncompressed and compressed states and has a first maximum inner width while uncompressed and a second maximum inner width, greater than the first maximum inner width, while compressed. The valve also includes a flex-tube piston surrounding the flex-tube insert and defining the radial boundaries of the fluid path. The flex-tube piston includes a piston head for positioning within the inlet port during the uncompressed state and outside the inlet port during the compressed state. The flex-tube piston also includes a bore that is carried by the piston head. The bore is closed when the piston head is within the inlet port and opened when the piston head is outside the inlet port. The flex-tube piston also includes a piston base for positioning proximal the outlet port and providing fluid communication with the outlet port. The flex-tube piston is responsive to movement of the flex-tube insert.
In more detailed aspects, the flex-tube insert includes at least one collapsible section having a maximum cross section when viewed along the axis of the fluid path. The maximum cross section defines the first and second maximum inner widths. In another aspect, each collapsible includes a first end, a second end, and a plurality of hinge assemblies. Each hinge assembly has a hinge and two plates including two substantially parallel edges, one of the edges is attached to the hinge for pivotal movement and the other of the edges is attached to one of either the first or second ends for pivotal movement. In another detailed facet, there are four hinge assemblies arranged so that the flex-tube insert has a substantially square cross section when viewed along the axis of the fluid path and the distance between opposing hinges of the hinge assemblies define the first and second maximum cross sections.
In a third aspect, the invention is directed to a valve for providing a fluid path between the inlet port and outlet port of a connector. The valve includes a collapsible section having a hollow interior defining the radial boundaries of the fluid path. The collapsible section is movable between uncompressed and compressed states and has a first maximum cross-sectional area while uncompressed and a second maximum cross-sectional area, greater than the first maximum cross-sectional area, while compressed. The valve also includes a piston head at one end of the collapsible section for positioning within the inlet port during the uncompressed state and outside the inlet port during the compressed state and a bore carried by the piston head. The bore is closed when the piston head is within the inlet port and opened and communicating with the interior of the collapsible section when the piston head is outside the inlet port. The valve also includes a piston base at the other end of the collapsible section for positioning proximal the outlet port and providing communication with the outlet port.
In a more detailed facet, the collapsible section includes at least one collapsible portion having a maximum cross-sectional area when viewed along the axis of the fluid path. The maximum cross-sectional area defines the first and second maximum cross-sectional areas. In another facet, each collapsible portion includes a first end, a second end, and a plurality of hinge assemblies. Each hinge has a hinge and two plates including two substantially parallel edges. One of the edges is attached to the hinge for pivotal movement and the other of the edges is attached to one of either the first or second ends for pivotal movement. The collapsible portion further includes a plurality of resiliently deformable webs joining the edges of adjacent hinge assemblies to seal the interior of the collapsible section. In a more detailed facet, there are three hinge assemblies arranged so that the collapsible portion has a substantially triangular cross section when viewed along the axis of the fluid path.
In a fourth aspect, the invention is related to a method of controlling the flow of fluid between an inlet port and an outlet port of a medical connector having a valve assembly defining a fluid path having an internal volume. The valve assembly has an inlet end disposed within the inlet port and an outlet end communicating with the outlet port. The inlet end carries a bore that is closed when within the inlet end and opened when outside the inlet port. The method includes the steps of increasing the internal volume of the fluid path while simultaneously opening the bore and subsequently decreasing the internal volume of the fluid path while simultaneously closing the bore.
In a more detailed aspect, the valve assembly is formed of a resiliently deformable material and the step of increasing the internal volume of the fluid path while opening the bore includes the steps of displacing the inlet end from the inlet port and expanding the valve assembly in a generally radial outward direction relative to the axis of the fluid flow path. In another aspect, the step of displacing the inlet end from the inlet port includes the step of inserting a male-Luer taper into the inlet port and applying pressure to the inlet end. In yet another facet, the step of decreasing the internal volume of the fluid path while closing the bore includes the steps of placing the inlet end in the inlet port and collapsing the valve assembly in a generally radial inward direction relative to the axis of the fluid flow path. In still another facet, the step of placing the inlet end in the inlet port comprises the step of removing the male-Luer taper from the inlet port.
In a fifth aspect, the invention is directed to a method of controlling the flow of fluid between an inlet port and an outlet port of a medical connector having an axially compressible valve assembly defining a fluid path having an internal volume. The valve assembly has an inlet end disposed within the inlet port and an outlet end communicating with the outlet port. The inlet end carryies a bore that is closed when within the inlet end and opened when outside the inlet port. The method includes the steps of maintaining the internal volume of the fluid path substantially constant while axially compressing the valve assembly and opening the bore; and subsequently maintaining the internal volume of the fluid path substantially constant while axially decompressing the valve assembly and closing the bore.
In a sixth aspect, the invention is related to a connector for medical use, adapted to facilitate the flow of fluid therethrough. The connector includes an inlet port, an outlet port and a valve assembly defining a fluid path between the inlet port and the outlet port. At least one of the inlet port, the outlet port and the valve assembly is formed to include an antimicrobial agent.